OmniCalcsImage Resizer & Compressor
Resize and compress images right in your browser — nothing is uploaded.
How to Use This Tool
Pick an image, set max width, quality and format, then process. Preview and download appear instantly.
- WebP gives the best size/quality balance for web use.
- Use 100% quality for lossless PNG-style output when needed.
Frequently Asked Questions
Is my image uploaded?
No. All processing happens locally with the Canvas API — your image never leaves your device.
Does resizing reduce quality?
Downscaling is generally visually lossless. Compression (quality below 100) is where the real file-size savings come from.
Which format should I choose?
WebP for photos on the web, JPEG for maximum compatibility, PNG for images needing transparency or sharp text.
Can I batch process images?
Not yet — this tool processes one image at a time. For bulk work, use a desktop tool.
Practical Example
A 4000 x 3000 photo of about 4.8 MB is loaded with max width 1200 px and 80% quality in WebP. The scale factor is min(1, 1200 / 4000) = 0.3, so the output is 1200 x 900 px, and the compressed WebP often drops to under half a megabyte — roughly a 90% file-size reduction.
- Height scales proportionally with the width, so the image is never distorted.
What Your Results Mean
- New dimensions — the width you set with the height scaled proportionally.
- File size — the exported size in B, KB or MB; smaller files load faster on the web.
- Quality — compression below 100% trades some detail for smaller files; 80% is a common balance.
- Format — WebP for the web, JPEG for compatibility, PNG for transparency and sharp text.